Image processing apparatus and method

ABSTRACT

Image processing apparatus and method perform a predetermined compression processing for an input original. A compression processing method or a receiver of compressed data is changed in accordance with a color/black-and-white status discrimination for the input original, or is set manually.

This application is a division of application Ser. No. 08/264,494 filedAug. 16, 1994, U.S. Pat. No. 5,666,216 is a division of application Ser.No. 08/031,198, filed Mar. 12, 1993, now U.S. Pat. No. 5,361,144, whichis a division of appliation Ser. No. 07/607,651, filed Oct. 31, 1990,now U.S. Pat. No. 5,220,417.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a color image processing apparatus and methodhaving the function of transmitting or receiving a color original.

2. Description of the Related Art

Conventional facsimiles used in facsimile communication, which has longbeen put into practical use, can transmit and receive only monochromatic(black-and-white) images. Accordingly, a facsimile communication circuit(abbreviated hereinafter as "circuit") network has of course been laidfor the purpose of dealing with monochromatic images.

Recently, however, demands for color facsimiles have appeared. Althoughvarious kinds of methods are being studied and developed in variousfields, the stage has not yet come wherein the methods are normalizedand generally utilized, but they are now being internationallyinvestigated. It is relatively easy in principle to configure a colorfascimile. However, since almost all facsimiles currently used are formonochromatic images, even if some facsimile stations adopt colorfacsimiles, the picture quality reproduced images is substantiallydeteriorated if most facsimiles installed at parties for transmission(the reception sides) are for monochromatic images, and so mutualcommunication becomes impossible. As a result, utilization of thecurrent, i.e. monochromatic, circuit becomes impossible if somecountermeasures are not taken. Accordingly, development of a method inwhich color facsimiles can be used while utilizing the current circuitwithout modification has been strongly demanded.

Techniques for discriminating whether an original has a black-and-whiteimage or a color image are described in U.S. Pat. No. 4,739,397 and U.S.Pat. No. 4,953,013. There is room for improvement, however, in theabove-described techniques from the viewpoint of transmission of colororiginals and black-and-white originals.

SUMMARY OF THE INVENTION

It is an object of the present invention to remove the above-describeddisadvantages in the prior art.

It is a further object of the present invention to provide a color imageprocessing apparatus capable of efficiently performing transmission andreception of image data.

These objects are accomplished, according to one aspect of the presentinvention, by an image processing apparatus comprising discriminationmeans for discriminating a color/black-and-white status of an inputoriginal having an image, and selection means for selecting a party fortransmitting image data obtained from the input original in accordancewith a result of discrimination by the discrimaination means.

According to another aspect, the present invention relates to an imageprocessing apparatus comprising discrimination means for discriminatinga color/black-and-white status of a predetermined amount of an inputoriginal, and compression means for compressing image data obtained,from the input original with different compression methods in accordancewith a result of discrimination by the discrimination means.

It is a still further object of the present invention to efficientlytransmit and receive black-and-white image data and color image data.

This object is accomplished, according to one aspect of the presentinvention, by an image processing apparatus comprising first outputmeans for outputting data subjected to color image compression, secondoutput means for outputting data subjected to black-and-white imagecompression, selection means for selecting between the first and secondoutput means in accordance with a kind of an apparatus at a party fortransmission, and transmission means for transmitting compressed datafrom the output means selected by the selection means.

It is still another object of the present invention to provide atransmission apparatus having an excellent operability.

This object is accomplished, according to one aspect of the presentinvention, by an image processing apparatus comprising first compressionmeans for performing compression for a black-and-white image on inputimage data, second compression means for performing compression for acolor image on input image data, selection means for selecting betweenthe first and second compression means, and setting means for setting afirst mode wherein the selection means performs the selection inaccordance with a color/black-and-white status of the input image dataand a second mode wherein the selection means performs the selection inaccordance with a manual key input.

According to another aspect, the present invention relates to an imageprocessing method comprising the steps of performing compression for ablack-and-white image for input image data, performing compression for acolor image for input image data, selecting between the first and secondcompression steps, and setting a first mode wherein the selection isperformed in accordance with a color/black-and-white status of the inputimage data at the selection step and a second mode wherein the selectionis performed in accordance with a manual key input at the selectionstep.

It is still a further object of the present invention to efficientlytransmit black-and-white images and color images.

These and other objects and aspects of the present invention will becomemore apparent from the following description made in reference to theaccompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a basic color separation apparatus accordingto a first embodiment of the present invention;

FIG. 2 is a diagram showing a time-serial signal composed of R (red), G(green) and B (blue);

FIG. 3, composed of FIGS. 3(a), 3(b), 3(c) and 3(d), includes blockdiagrams showing the basic configuration of a color image processingapparatus according to the present invention;

FIG. 4 is a block diagram showing a color/black-and-white originalautomatic discrimination circuit;

FIG. 5 is a diagram showing how black-and-white binary data are producedfrom color binary data;

FIG. 6 is a block diagram showing another color/black-and-white originalautomatic discrimination circuit;

FIG. 7 is a diagram showing expressions for transforming signals R, Gand B into signals L, S and H;

FIG. 8 is a diagram showing a network using a color image processingapparatus according to the present invention;

FIG. 9 is a flowchart illustrating communication performed using a colorimage processing apparatus according to the present invention; and

FIGS. 10, 11, 12(a), composed of FIGS. 10(A) and 10(B), 11(A) and 11(B),12(a1) and 12(a2), respectively, 12(b) and 12(c) are flowcharts showingother embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be explainedwith reference to the drawings.

First Embodiment

FIG. 1 is a diagram showing a basiccolor separation apparatus installedat the transmission side of a color facsimile. In FIG. 1, there areshown a color original 1, a light source 2 for illuminating theoriginal, half-mirrors 3a and 3b, lenses 4a, 4b and 4c, red (R), green(G) and blue (B) filters 5a, 5b and 5c, sensors for photoelectricconversion, such as CCD line sensors or the like, 6a, 6b and 6c, signaloutput terminals 7a, 7b and 7c, amplifiers 8a, 8b and 8c, A/D converters9a, 9b and 9c, a color-signal transmission controller 10, a circuit 11,such as a public circuit or the like, and a color separationphotoelectric conversion unit 12.

The original 1 is illuminated by light emitted from the light source 2,and part of light reflected from the original 1 is first branched by thehalf-mirror 3a in the direction of arrow I. The branched light,including only red component light after passing the red filter 5a, issubjected to photoelectric conversion by the sensor 6a for red color,and is output to terminal 7a as an electrical signal corresponding tored color. A part of the light transmitted through the half-mirror 3a inthe direction of arrow IV is branched by the second half-mirror 3b inthe direction of arrow II. The branched light, including only greencomponent light after passing the green filter 5b, is subjected tophotoelectric conversion by the sensor 6b for green color, and is outputto terminal 7b as an electrical signal corresponding to green light. Thelight proceeding in the direction of arrow III after passing the secondhalf-mirror 3b, and including only blue component light as a result ofpassing the blue filter 5c, is subjected to photoelectric conversion bythe sensor 6c for blue color and is output to terminal 7c as anelectrical signal corresponding to blue color.

All the color signal components obtained as a result of theabove-described color separation have analog values. Hence, afterpassing the respective dedicated amplifiers 8a, 8b and 8c, these signalsare input to the respective dedicated A/D converters 9a, 9b and 9c,where the signals are subjected to digital processing. In FIG. 1, thedigitized signals are indicated by symbols V_(R), V_(G) and V_(B).

These parallel signals V_(R), V_(G) and V_(B) are input to thecolor-signal transmission controller 10, where they are converted into atime-serial signal (a serial signal) in the order of first bit, secondbit, third bit, --as shown in FIG. 2 by RGB, RGB, --, for example, froma signal for a partial image at the left end on the first lateral lineon the original 1 to signals in the right direction utilizing atime-sharing function of a decoder (parallel-serial converter) 18 withinthe controller 10, and the converted signal is transmitted to thecircuit 11.

However, since the fascimiles which have already become wide spread aremonochromatic types, there has been the disadvantage that, even if colorseparation is performed by a method as described above, an image cannotbe normally reproduced due to a lack of color identifying capability ifa party for transmission has a monochromatic facsimile not having acolor reproducing function, and transmission and reception of an imagebecomes impossible as described above.

It is not impossible to reproduce color by synthesizing fascimilesignals. That is, it is easy to synthesize color signals by replacingthe signal transmission controller 10 in the transmission system shownin FIG. 1 with a signal reception controller and inverting thetransmission channels for respective color signals. The only obstacle isthat almost all facsimile stations currently installed havemonochromatic facsimiles. As a result, the above-described inconveniencethereby occurs.

FIG. 3(a) is a block diagram of a color image processing apparatus ofthe present embodiment.

First, an explanation will be provided of the entire flow in a colorfacsimile by reference to FIG. 3(a).

In FIG. 3(a), a scanner unit 301 reads an original, and outputsrespective one-bit data for R, G and B for one picture element.

FIG. 3(a) shows the configuration of the scanner unit 301. Intransmission, an image on an original is converted into electricalsignals by photoelectric conversion devices 1301, such as CCD linearsensors or the like, while being subjected to optical color separationin the scanner unit 301, and the converted signals are subjected toanalog-to-digital conversion by an A/D converter 1302. Digitizedthree-color reflective signals from the original pass a shading circuit1303 for correcting variations in the light source, the photoelectricconversion devices and the like, and are input to an input colorcorrection circuit 1304 for, for example, matching the signals withspectral characteristics of the NTSC system. The signals are then inputto a masking circuit 1305, where color correction (masking processing)is performed according to 3×3 matrix conversion or the like. Therespective color signals are multi-value data (for example, 24-bit datacomposed of 8-bit data for each color) up to this point. However, sincethe current transmission channel has a narrow band, too muchtransmission time is needed. Hence, it is practical to transmit thesignals as binary data with a resolution of 400 dpi (dots per inch).Accordingly, the image data are binary coded by a binary coding circuit1306, are converted into a serial signal by a parallel-serial converter1307, and are output from the scanner 301. As a result, the signaloutput from the scanner 301 is composed of one bit for each of the NTSCsignals R, G and B for one picture element, that is, 3 bits/pixel(picture element) in total for three colors.

Output data from the scanner 301 are input to a buffer memory 311 withina controller 325 in FIG. 3(a). The buffer memory 311 is a component,composed of a line memory, for storing data for a few lines. A unit 312for discriminating whether an original is a black-and-white original ora color original performs switching so that color separation data for anoriginal are input to a color compression unit 313 or to ablack-and-white compression unit 315 according either to a result ofautomatic discrimination between a black-and-white original and a colororiginal, or to manual setting of a color/black-and-white switchingbutton on an operation panel 303. As shown in FIG. 3(b), thecolor/black-and-white discrimination unit 312 includes a discriminationcircuit 201, a selector 202 for selecting whether data from the BUF 311are input to a color/black-and-white conversion unit 314 (side A) or tothe color compression unit 313 (side B) according to a result ofdiscrimination by the discrimination circuit 201, and an operation unit203 for performing manual setting of color/black-and-white status. Theselector 202 selects the side A when the output from thecolor/black-and-white discrimination circuit 201 is 0 (black-and-white),and selects the side B when the output from the circuit 201 is 1(color). In the case of manual setting, manual setting using theoperation unit 203 is performed in preference to discrimination by thediscrimination circuit 201. The side A is selected when setting from theoperation unit 203 is S₁ =0 (black-and-white), and the side B isselected when setting is S₁ =1 (color), irrespective of the value S₀ inthe selector 202. In a service mode, it is possible to set a defaultmode when power of a power supply is turned on to color orblack-and-white by a mode switch.

A unit 314 converts data discriminated as from a black-and-whiteoriginal as a result of automatic or manual color/black-and-white statusdiscrimination by the unit 312 from a three-color signal into ablack-and-white signal.

The color compression unit 313 performs compression of image dataincluding color information using a compression algorithm, such as blockcoding for performing codings by performing, for example, orthogonaltransformation for every block, vector quantization, ADCT (adaptivediscrete cosine transform) or the like. The black-and-white compressionunit 315 performs data compression by a compression algorithm, such asMH, MR, MMR or the like, used in a conventional black-and-whitefacsimile.

At this time, when black-and-white data are provided as a result ofmanual or automatic discrimination, the data can be transmitted ifstandard compression for a G3 FAX (facsimile) or a G4 FAX has beenperformed by the black-and-white compression unit 315, even if a partyfor transmission has a G3 FAX or a G4 FAX. A G4 FAX is for a digitalnetwork for ISDN (integrated services digital network), while a G3 FAXis for an analog network utilizing a telephone circuit. Hence, a modemis needed for a G3 FAX.

Black-and-white data transmitted from a G4 FAX or a G3 FAX are stored ina hard disk 316, and are decoded by a black-and-white expander 317. Thedata are composed of only black information at this time. Hence, when,for example, an ink-jet printer 302 for simultaneously recording fourcolors is used, data for yellow (Y), magenta (M) and cyan (C) made 0 fornot performing printing (Y=M=C=0) are added, and the resultant data aretransmitted to a buffer memory 323. Signal K for black is calculated byK=1-Y_(e). The signal Y_(e) will be described later. It becomes therebypossible to perform an operation totally identical to that for colorrecording.

When the transmitted data are color data, the data output from the harddisk 316 are subjected to color expansion by a color expander 319. Acolor correction/black formation unit 320 then performs color correctionand black formation in order to generate from an NTSC signal a signalmatched with color materials used in the printer 302. A multivaluedoutput from the color correction/black formation unit 320 is subjectedto binary coding by a density-preserving-type binary coding circuit 321,from which 4-color 4 bits/pixel data are input to an output buffermemory BUF 323.

Data from the BUF 323 are output in the form of 4 bits/pixel either inthe case of black-and-white data or in the case of color data. Theprinter 302 is a color printer, which, for example, uses an ink-jetrecording unit having recording heads of the bubble jet system, andperforms simultaneous recording by four heads for Y, M, C and K arrangedin parallel. Accordingly, YMCK 4 bits/pixel data 308 from the controller325 are subjected to four-color printing while subjected to buffering bya registration unit for the heads. In the case of black-and-white,printing is performed with Y=M=C=0 and in accordance with 0 or 1 ofsignal K.

The bubble jet system is a system in which a liquid droplet is emittedby boiling a film by a thermal energy.

An outline of the color facsimile of the present embodiment has now beenprovided. Next, an explanation will be provided of thecolor/black-and-white automatic disrimination unit which is an essentialunit in the present embodiment, and a method for generating ablack-and-white image signal from a color image signal.

FIG. 4 shows an example of the color/black-and-white automaticdiscrimination unit. In FIG. 4, it is assumed that binary-coded NTSC 3bits/pixel signals 401 for R, G and B are input, and the values of dataat a certain point (i, j) are represented by r, g and b. If the signalsare subjected to multivalue processing with, for example, pictureelements 2n+1 and 2m+1 by a multivalue coding conversion unit 402,converted signals are expressed by the following expression (1):##EQU1##

Since the input signals 401 are binary signals having values of 0 or 1,it is difficult to calculate a color for every picture element, and itis not necessary to perform black-and-white/color discrimination forevery picture element. What is necessary to determine is what colorthere is within an average area. If the numbers n and m are too large,there occurs a possibility of misdiscrimination at fine-line portionshaving color characters or the like. Hence, the value n=m=1-10 isreasonable.

Data subjected to multivalue processing by expression (1) are subjectedto conversion between R, G and B in NTSC and X, Y and Z in CIE accordingto the following expression (2). Using a result obtained by expression(2), lightness L and colors "a" and "b" are calculated according to thefollowing expression (3): ##EQU2##

    L=116(Y/Y.sub.0).sup.1/3 -16

    a=500[(X/X.sub.0).sup.1/3 -(y/y.sub.0).sup.1/3 ]           (3).

    b=200 [(Y/Y.sub.0).sup.1/3 -(Z/Z.sub.0).sup.1/3 ]

The color component is given by the following expression (4): ##EQU3##

In FIG. 4, circuits 402, 403, 404 and 405 perform calculations accordingto expressions (1), (2), (3) and (4), respectively. A circuit 406determines an achromatic range. The threshold value "th" in the circuit406 becomes "a" when 1≦a (0<a<255) and the circuit 406 determines thatthe original is an achromatic, that is, a black-and-white original. Anaccumulator 407 counts the number of picture elements for which "th">"a"for a color in each picture element, and determines that the original isa color original when the number is at least a predetermined number ofpicture elements, and the original is a black-and-white original whenthe number is less than the predetermined number. The predeterminednumber of picture elements is made a reference for the purpose ofpreventing misdiscrimiriation due to an error in reading by the scanner301 or the like.

The above-described discrimination of whether the original is colored orblack-and-white is performed for every page of the original.Accordingly, in automatic discrimination, reading is performed firstassuming a color original, and data for one page subjected to colorcompression by the color compression unit 313 are stored in the harddisk 316 while discriminating the data by the discrimination circuit312. When the count number in the accumulator 407 is small at the end ofreading one page and so it is discriminated that the original isblack-and-white, the data stored in the disk 36 are input to thecolor/black-and-white discrimination unit 312 by the color expander 319.Since it has been known that the data flown from the discrimination unit312 are for black-and-white, the color data are converted intoblack-and-white data by the color/black-and-white conversion unit 314,and the converted data are written again in the hard disk 316 by theblack-and-white compression unit 315. The color data which werepreviously input are deleted after black-and-white conversion of thedata subjected to feedback. Hence, the data are stored in the hard disk316 in a minimum capacity.

FIG. 5 is a diagram for explaining a method for obtainingblack-and-white binary data from color binary data. Black-and-white dataare produced using, for example, a set of (R1, G1, B1), where R, G and Bare binary data output from the scanner 301. When the correspondingimage is manually set to a black-and-white mode using the operationpanel 203 (303 in FIG. 3(a)), or it is discriminated as ablack-and-white original by the color/black-and-white automaticdiscrimination unit 312, a black-and-white signal is produced accordingto the following expression (5):

    Y.sub.1 =0.299R+0.587G+0.114B                              (5).

Signals R, G and B, being binary data, are 0 or 1. Calculation usingexpression (5) is performed while performing conversion 0→0 and 1→255.It is assumed that black-and-white binary coded data K is K=0 (a dot isnot printed) if Y₁ ≧128, and K=1 (a dot is printed) if Y₁ <128.

Expression (5) is for the case of signals subjected to color separationfrom NTSC signals. When other signals are input, black-and-white signalsmay also be obtained using a similar basic concept, though coefficientshave different values.

As described above, according to the present embodiment, by manually orautomatically setting the black-and-white/color status of an original,and by using a compression method for a black-and-white image for ablack-and-white original, and using a compression method for a colorimage for a color original, compression effeciency can be greatlyincreased in the case of a black-and-white original.

Furthermore, by providing the color/black-and-white conversion unit 314,it is possible to use a compression algorithm for black-and-whiteinformation even when chromatic picture elements exist in a part of anoriginal. Moreover, it becomes possible to communicate with existingfacsimiles in formats G3, G4 and the like.

In addition, since the system is arranged so that manual discriminationmay also be performed as well as automatic discrimination, it ispossible to perform transmission and reception using a compressionalgorithm for black-and-white information if the user wants to transmitand receive a color original in a short time, or when it is notnecessary to transmit an image in color.

Second Embodiment

The basic configuration of a second embodiment is identical to thatshown in FIG. 3.

In the present embodiment, in place of the conversion from R, G and Bsignals in NTSC into signals L, "a" and "b" used incolor/black-and-white discrimination in the first embodiment, conversioninto signals H, L and S is used.

That is, the present embodiment differs from the first embodiment inthat a HLS conversion unit 408 as shoiwn in FIG. 6 is provided in placeof the circuits 403 and 404 for the conversion into L, "a" and "b".

Expression for conversion from signals R, G and B into signals H, L andS is shown in FIG. 7. The color component is provided by the followingexpression (6): ##EQU4## A method for determining an achromatic rangefrom the value 1 is the same as that in the first embodiment.

Conversion from signals R, G and B is not limited, to theabove-described signals L, "a" and "b", and signals H, L and S, but anidentical discrimination operation may be performed using parametersseparated into a lightness signal and hue signals and capable ofdiscriminating between chromatic/achromatic properties for every pictureelement, such as signals L, u and v, signals Y, I and Q, or the like.Even if parameter conversion is not performed, color/black-and-whitediscrimination may be performed, for example, according to thedistribution of chromatic and achromatic colors in Max (R, G, B)-Min (R,G, B) space.

Third Embodiment

FIG. 8 shows an example of utilization of color facsimiles having thecolor/black-and-white automatic discrimination units in the firstembodiment. In FIG. 8, there are shown ISDN (a digital communicationnetwork) 601, PSTN (a public telephone circuit) 602, and a colorfacsimile (CFAX) 604 having a color/black-and-white automaticdiscrimination unit used in corporation "C" 603. In corporation "A" 605,a color facsimile (CFAX) 606 is connected to the ISDN through line F,and a G4 black-and-white facsimile 607 is also connected to the ISDNthrough line E. In corporation "B", a color facsimile (CFAX) 609 isconnected to the ISDN through line C, and a G3 black-and-white facsimile610 is connected to the PSTN through line D.

When both color and black-and-white originals are transmitted fromcorporation "C" 603 to corporation "A" 605, the CFAX 604 can transmitimage data to the CFAX 606 on Line E via the ISDN through line A usingits color/black-and-white automatic or manual discrimination unit 312 inthe case of a color original. In the case of a black-and-white original,transmission is automatically switched to the G4 black-and-white FAX607, and high-quality black-and-white image data can be transmitted athigh speed. Similarly, image data can be transmitted to the separatefacsimiles in corporation "B" by performing color/black-and-whitediscrimination.

The CFAXs 604, 606 and 609 used in the present embodiment are imageprocessing apparatuses explained in the first embodiment. Lines E and Fconnected to the CFAX 606 and the G4FAX 607 in corporation "A",respectively, and lines C and D connected to the CFAX 609 and the G3FAX610 in corporation "B", respectively, are registered whether they arefor color FAXs or black-and-white FAXs according to their addresses, andthe system is arranged so that the CFAX 604 in corporation "C" at thetransmission side can select the registration.

When the discrimination unit 312 discriminates that the original has acolor image, image data are transmitted to the CFAX 606 or the CFAX 609.When the discrimination unit 312 discriminates that the original has ablack-and-white image, image data are transmitted to the G4FAX 607 orthe G3FAX 610.

When corporation "A" or "B" at the reception side has only a colorfacsimile, data are transmitted to the color facsimile. When only ablack-and-white facsimile is owned, data are transmitted whileperforming compression for black-and-white information by theblack-and-white compression unit 315 even if the original isdiscriminated as a color original. Thus, it becomes possible to transmitdata for color originals to a color facsimile, and data forblack-and-white originals to a facsimile dedicated for black-and-whiteimages, even if color originals and black-and-white originals are mixed.Hence, the present embodiment provides very significant effects from theviewpoint of communication speed, image discrimination, cost and thelike.

In the ISDN or the like, since it is possible to assign a plurality ofsubaddresses for one circuit, black-and-white and color facsimiles maybe installed in the subaddresses. In this case, according to the presentembodiment, in consideration of the current status that very few colorfacsimiles have been used, the system is arranged so as to be able toalso communicate with G4 and G3 machines. That is, if a black-and-whiteoriginal is mixed among color originals, a black-and-white signal isautomatically produced, data are compressed in a black-and-white mode toincrease compression efficiency, and recording is performed using onlyblack ink in reception. It is thereby possible to provide betterdefinition in fine-line portions, such as character portions or thelike, than in recording of black by superposing three colors, and toprovide higher picture quality in transmission of black-and-whiteoriginals. For that purpose, a color/black-and-white automaticdiscrimination unit is provided, and a black-and-white setting switch isprovided on an operation panel in order to set a black-and-white mode. Aluminance signal is thereby obtained from three-color data, andblack-and-white data are obtained by binary coding the luminance signal.Thus, it is possible to realize communication with conventionalfacsimiles which are not color facsimiles.

Fourth Embodiment

Although the basic configuration of an image processing apparatus of afourth embodiment is identical to that of the first embodiment, a methodof color/black-and-white discrimination is different in the presentembodiment.

That is, in the first embodiment, color/black-and-white discriminationis performed for every page of an original. In such a discriminationmethod, however, if data are transmitted while selection is performedbetween a color printer and a black-and-white printer at the receptionside according to a result of automatic (or manual) discrimination foran original, as in the third embodiment, when color pages andblack-and-white pages are mixed in an original composed of severalpages, one original is dispersed in a plurality of printers. Hence,there occurs inconvenience particularly when a black-and-white printerand a color printer are separately installed. In the present embodiment,such a problem is solved by performing color/black-and-whitediscrimination for every original.

The configuration of the present embodiment will be explained byreference to FIG. 3.

In FIG. 3, the color/black-and-white discrimination unit 312discriminates color/black-and-white of an original for every page as inthe third embodiment. Data of a page discriminated as having a colorimage are compressed using an algorithm for color image compression bythe color compression unit 313, and the compressed data are stored inthe hard disk 316. On the other hand, data of a page discriminated ashaving a black-and-white image pass through the color/black-and-whiteconversion unit 314, are compressed using an algorithm forblack-and-white image compression by the black-and-white compressionunit 315, and the compressed data are stored in the hard disk 316.

In the present embodiment, as shown in FIG. 3(c), a counter 204 forcounting outputs having a value 1 (that is, pages discriminated ashaving color images) among output signals from the color/black-and-whitediscrimination circuit 201 is provided. When discrimination for aplurality of pages has been performed, the entire original istransmitted to a color facsimile (the CFAX 606 or the CFAX 609 in FIG.8) except when the count value is 0, and color output is performed.According to the present embodiment, when an original is composed of aplurality of pages, color/black-and-white discrimination is performednot for every page, but for every original. Hence, even an originalcomposed of both black-and-white and color pages can be transmitted in aunit to a single reception apparatus. Furthermore, since compression fora black-and-white image is performed for black-and-white pages at thattime, communication time can be shortened, and cost can be reduced.

Fifth Embodiment

Although, in the foregoing third embodiment, the kinds of facsimiles atthe reception side are previously registered as addresses at thetransmission side, and a party for transmission is selected inaccordance with the color/black-and-white status of an original, thekind of facsimile at the reception side may be confirmed in a procedurebefore starting communication, and a facsimile at the transmission sidemay be selected in accordance with the confirmed result, as in thepresent embodiment.

The present embodiment will now be explained by reference to theflowchart shown in FIG. 9.

An original is read for an amount of one page by the color separationapparatus 12 (S1), and the color/black-and-white status of the originalis then discriminated by the color/black-and-white discrimination unit312 (S2). When the original has been discriminated as a color original,color image compression is performed by the color compression unit 313(S3). When the original has been discriminated as a black-and-whiteoriginal, black-and-white compression is performed by theblack-and-white compression unit 315 (S4). In either case, compresseddata are stored in the hard disk 316.

If the original is composed of a plurality of pages, the above-describedprocessing is repeated for all pages (S5), and the process proceeds toprotocol with the reception side when the processing has ended (S6).

If all pages of the original are black-and-white (S7), and there is ablack-and-white facsimile at the reception side (S8), data aretransmitted to the black-and-white facsimile (for example, the G4FAX 605or the G3FAX 610 in FIG. 8) (S9). If all pages of the original areblack-and-white (S7), but the reception side has only a color facsimile(S8), black-and-white image data are transmitted to the color facsimile(S10). In this case, since the color facsimile at the reception side hasboth the color expander 319 and the black-and-white expander 317, asshown in FIG. 3(a), the color facsimile can reproduce a black-and-whiteimage even if compressed data of the black-and-white image are received.

If at least one page of the original has been discriminated as colored(S7), and there is a color facsimile (for example, the CFAX 606 or 609in FIG. 8) at the reception side (S11), data are transmitted to thecolor facsimile (S12). If there is no color facsimile at the receptionside, data subjected to color image compression among image data storedin the hard disk 316 are expanded by the color expander 319, are thenconverted into black-and-white image data by the color/black-and-whiteconversion unit 314. The converted data are subjected to black-and-whiteimage compression by the black-and-white compression unit 315, and theresultant data are stored again in the hard disk 316. The color data arethus switched to black-and-white compression (S13), and are transmittedto a black-and-white facsimile (S14).

According to the present embodiment, after black-and-white/colordiscriminating for an original, the transmission side performstransmission after discriminating by a protocol whether an apparatus atthe reception side is a facsimile capable of receiving color data or afacsimile for black-and-white data. Hence, an appropriate selection maybe performed even if it has not previously been known which type ofapparatus the reception side has.

Furthermore, since both the color/black-and-white status of an originaland the color/black-and-white status of an apparatus at the receptionside are considered, efficiency can be further increased than whencontrol is performed according to discrimination for either one of theabove-described two items.

Sixth Embodiment

FIG. 10 shows a flowchart of a sixth embodiment of the presentinvention.

In the present embodiment, a black-and-white transmission mode and acolor transmission mode are manually selected using a mode switch on theoperation panel 303, and processing is performed in accordance with thekind of facsimile at the reception side.

First, either one of the black-and-white transmission mode and the colortransmission mode is manually set using the operation unit 203 on theoperation panel 303 (S21). In the color transmission mode, color imagecompression is performed irrespective of black-and-white/color of anoriginal, and the compressed data are stored in the disk (S22 and S23).Protocol is then executed (S24). If there is a color facsimile at thereception side, the contents of the disk are transmitted to the colorfacsimile without modification (S25 and S26). If there is no colorfacsimile at the reception side, a voice warning is performed by awarning means (not shown), and the fact is also displayed on aliquid-crystal display on the operation panel 303 (S27). If a command toperform black-and-white transmission is issued through the operationpanel 303 (S28), image data subjected to color image compression areconverted into data subjected to black-and-white image compression(S29), and black-and-white transmission is performed (S30). Ifblack-and-white transmission is not performed, the process isterminated.

When the transmission mode is a black-and-white transmission mode,black-and-white image compression is performed, the compressed data arestored in the disk (S31), and protocol is executed (S32). If there is ablack-and-white facsimile (including a color facsimile having a functionof receiving black-and-white compression data) at the reception side,black-and-white transmission is performed (S33 and S34). If there is noblack-and-white facsimile, the voice warning and display are performedas described above (S35). When color transmission is performed, data areconverted into data subjected to color image compression (S37), andcolor transmission is performed (S38). When color transmission is notperformed, the process is terminated (S36).

According to the present embodiment, by performing warning and displaywhen communication intended by the operator cannot be performed when amanual mode is set, it is possible to confirm an image to be output atthe reception side, and so improve operability.

Seventh Embodiment

FIG. 11 shows a flowchart of a seventh embodiment of the presentinvention.

In the present embodiment, an auto color selection mode (ACS mode) forautomatically discriminating the black-and-white/color status of anoriginal, a color transmission mode and a black-and-white transmissionmode are manually selected using a mode switch on the operation panel303.

An explanation will now be provided mainly of steps different from thoseshown in FIG. 9.

First, mode setting is performed using a mode switch on the operationpanel 303 (S40). In the case of the ACS mode, the same processings asthose in FIG. 9 (steps S1-S5) are performed (S41). If the color mode hasbeen selected, all pages are subjected to color image compression, andthe compressed data are stored in the disk (S43). In the case of theblack-and-white transmission mode, black-and-white image compression isperformed, and the compressed data are stored in the disk (S44).

The subsequent processings are nearly identical to those shown in FIG.9, except that the voice warning and display as shown in FIG. 10 areperformed (S45 and S47), and data subjected to black-and-white imagecompression are converted into data subjected to color image compressionin the case of a color facsimile incapable of receiving data subjectedto black-and-white compression (S46).

In the present embodiment, since a mode for automatically discriminatingthe black-and-white/color status of an original and a mode for manuallyassigning black-and-white transmission and color transmission,efficiency in processing is increased when, for example, a colororiginal is transmitted in black-and-white.

Eighth Embodiment

FIG. 12 shows an eighth embodiment of the present invention.

In the present embodiment, a protocol is executed before imagecompression, and conversion of compressed data becomes unnecessary.

Mode setting (S51) is the same as in the case of FIG. 11. Next, theprotocol is executed (S52), and confirms whether a facsimile at thereception side is a black-and-white facsimile or a color facsimile. Ifthe black-and-white transmission mode has been set and the receptionside has a black-and-white facsimile (S53 and S54), black-and-whiteimage compression is performed (S55), and the compressed data aretransmitted to the black-and-white facsimile (S56). If the receptionside has a color facsimile incapable of receiving data subjected toblack-and-white compression, the voice warning and display are performedas described above (S57). When color transmission is performed, colorimage compression is performed the compressed data are stored in thedisk (S59), and the data are transmitted to the color facsimile (S60).When color transmission is not performed, the process is terminated(S58).

If the color transmission mode has been set (S61) and the reception sidehas a color facsimile, the above-described steps S59 and S60 areperformed (S62). If the reception side does not have a color facsimile,the voice warning and display are performed (S63), and the operator isasked whether or not black-and-white transmission is to be performed.When black-and-white transmission is performed, the above-describedsteps S55 and S56 are performed. When black-and-white transmission isnot performed, the process is terminated.

As shown in FIG. 12(b), when the ACS mode has been set, if the receptionside has a color facsimile, black-and-white/color discrimination for theoriginal at steps S1-S5 shown in FIG. 9 is performed. If all pages ofthe original are black-and-white and a color facsimile at the receptionside can receive black-and-white data (S66 and S68), data aretransmitted to the color facsimile (S60). If at least one color page isincluded in the original, or if a color facsimile at the reception sidecannot receive black-and-white data while all pages of the original areblack and white, the black-and-white pages are converted into colorcompression (S67), and the data are transmitted to the color facsimile(S60).

In place of the flow shown in FIG. 12(b), prescanning may be performedin order to discriminate black-and-white/color of the original, as shownin FIG. 12(c).

That is, if the reception side has a color facsimile at step S61, allpages of the original are subjected to prescanning (S71). If all pagesare black and white, and the reception side can receive data subjectedto black-and-white compression (S72 and S73), black-and-white imagecompression is performed, the compressed data are stored in the disk(S74), and the data are transmitted to the color facsimile (S60). If atleast one color page is included in the original, or if the receptionside cannot receive data subjected to black-and-white compression, theprocess shifts to steps S59 and S60.

According to the present embodiment, since priority is given todiscrimination for the kind of an apparatus at the reception side, thenecessity to change compression processing is reduced, and so efficientprocessing can be performed.

The above-described control including protocol is performed by a CPUwithin the controller 325. The control unit including the CPU comprisesa ROM storing programs for control, a RAM and the like.

Although, in the foregoing embodiments, input signals are signals R, Gand B, input signals may be a combination of other color-componentsignals, such as Y (yellow), M (magenta) and C (cyan), or the like.

Input signals are not necessarily those as a result of direct reading ofan image of an original by a CCD scanner, but may also be outputs from ahost computer, outputs from a filing system using magnetic disks,outputs from a still-picture video camera or a video camera, or thelike.

Although, in the foregoing embodiments, a BJ (bubble-jet) printer havinga head wherein a liquid droplet is ejected by ebullition of a thin filmcaused by heat energy, as mentioned in U.S. Pat. No. 4,723,129 and U.S.Pat. No. 4,740,793, is used as the printer, any printer capable offorming a color image may also be used, such as a color dot printer, acolor ink-jet printer, a color laser-beam printer, a thermal colorprinter, or the like.

Although an explanation has been provided for the case of binary data,the same principle may also be used in the case of transmission andreception of multivalue data. When performing transmission and receptionof multivalue data, the binary coding unit in the scanner 301 and themultivalue coding unit 402 in the color/black-and-white discriminationunit 312 become unnecessary.

Black-and-white/color discrimination is not necessarily performed forevery page. That is, the discrimination may be performed for at least apredetermined number of pages in a unit. The determination may also beperformed for every half page. Color portions and black-and-whiteportions in a page become more easily separated as a unit fordiscrimination is smaller, and hence it is possible to adopt compressionmethods suited for the respective portions.

As described above, according to the present invention, it is possibleto increase efficiency in transmission and reception of color imagedata.

The present invention is not limited to the above-described embodiments,but various changes and modifications may be made within the scope ofthe appended claims.

What is claimed is:
 1. An image processing apparatus comprising:firstgenerating means for generating digital image data consisting of aplurality of color components; color image compression means forcompressing the digital image data into color-image-compressed imagedata by using a color image compression method; storing means forstoring the color-image-compressed image data; receiving means forreceiving a predetermined instruction which is different from thedigital image data; second generating means for selectively generating,or not generating, monochromatic-compressed image data from thecolor-image-compressed data, based on the contents of the predeterminedinstruction received by the receiving means; and transmitting means forselectively transmitting the color-image-compressed image data or themonochromatic-compressed image data.
 2. An image processing apparatusaccording to claim 1, wherein said transmitting means is able totransmit the monochromatic-compressed image data or thecolor-image-compressed image data via an ISDN line.
 3. An imageprocessing apparatus according to claim 1, wherein said transmittingmeans is able to transmit the monochromatic-compressed image data via aPSTN line.
 4. An image processing apparatus according to claim 1,wherein the predetermined instruction is produced based on a kind of areception apparatus.
 5. An image processing apparatus according to claim1, wherein the generation of the monochromatic-compressed image data bysaid second generating means is performed when the reception apparatusis a monochromatic image processing apparatus.
 6. An image apparatusaccording to claim 1, wherein said color image compression meanscomprises means for orthogonally transforming the digital image data. 7.An image processing apparatus according to claim 1, wherein themonochromatic-compressed image data is generated by using ablack-and-white image compression method.
 8. An image processingapparatus according to claim 1, wherein the color-image-compressed imagedata is stored in a hard disc.
 9. An image processing apparatusaccording to claim 1, wherein the monochromatic-compressed image data istransmitted to a bubble jet printer.
 10. An image processing apparatusaccording to claim 1, further comprising reading means for reading anoriginal and generating image data.
 11. An image processing apparatusaccording to claim 1, wherein the plurality of color components includesred, blue and green components.
 12. An image processing apparatusaccording to claim 1, further comprising color correction means forcorrecting color of the digital image data generated by said firstgenerating means.
 13. An image processing apparatus according to claim1, further comprising conversion means for performing parallel-serialconversion of the digital image data generated by said first generatingmeans.
 14. An image forming method comprising the steps of:generatingdigital image data consisting of a plurality of color components;compressing the digital image data into color-image-compressed imagedata by using a color image compression method; storing thecolor-image-compressed image data in a memory; receiving a predeterminedinstruction which is different from the digital image data; selectivelygenerating, or not generating, monochromatic-compressed image data fromthe color-image-compressed image data, based on the contents of thepredetermined instruction received in the receiving step; andselectively transmitting the color-image-compressed image data or themonochromatic-compressed image data.